Prabhu Thirusangu

Synthesis and tumor inhibitory activity of novel coumarin analogs targeting angiogenesis and apoptosis.

A sequence of coumarin analogs 5a-j was obtained by multi step synthesis from hydroxy benzophenones (1a-j). The in vitro antiproliferative effect of the title compounds was tested against Ehrlich ascites carcinoma (EAC) and Daltons lymphoma ascites (DLA) cell lines. Among the series, compound 5c with bromo group in the benzophenone moiety was endowed with excellent antiproliferative potency with significant IC50 value. Further, in vivo antitumor effect of compound 5c against murine EAC and solid DL tumor model system was evident by the extended survivality. The tumor inhibitory mechanism of compound 5c was due to the antiangiogenesis and promotion of apoptosis. These results suggest possible applications of compound 5c which could be developed as a potent anticancer drug in the near future.

Synthesis, angiopreventive activity, and in vivo tumor inhibition of novel benzophenone-benzimidazole analogs.

AIM The development of anticancer drugs with specific targets is of prime importance in modern biology. This study investigates the angiopreventive and in vivo tumor inhibition activities of novel synthetic benzophenone-benzimidazole analogs. MAIN METHODS The multistep synthesis of novel benzophenone-benzimidazole analogs (8a-n) allowing substitution with methoxy, methyl and halogen groups at different positions on the identical chemical backbone and the variations in the number of substituents were synthesized and characterized. The newly synthesized compounds were further evaluated for cytotoxic and antiproliferative effects against Ehrlich ascites carcinoma (EAC) cells. The potent lead compounds were further assessed for antiangiogenic effects in a CAM model and a tumor-induced vasculature in vivo model. The effect of angioprevention on tumor growth was verified in a mouse model. KEY FINDINGS The cytotoxicity studies revealed that compounds 8f and 8n are strongly cytotoxic. Analyzing the structure-activity relationship, we found that an increase in the number of methyl groups in addition to methoxy substitution at the para position of the benzoyl ring in compound 8n resulted in higher potency compared to 8f. Furthermore, neovessel formation in in vivo systems, such as the chorioallantoic membrane (CAM) and tumor-induced mice peritoneum models, was significantly suppressed and reflected the tumor inhibition observed in mice. SIGNIFICANCE These results suggest the potential clinical application of compound 8n as an antiangiogenic drug for cancer therapy.

BP-1T, an antiangiogenic benzophenone-thiazole pharmacophore, counteracts HIF-1 signalling through p53/MDM2-mediated HIF-1α proteasomal degradation

Hypoxia is a feature of all solid tumours, contributing to tumour progression. Activation of HIF-1α plays a critical role in promoting tumour angiogenesis and metastasis. Since its expression is positively correlated with poor prognosis for cancer patients, HIF-1α is one of the most convincing anticancer targets. BP-1T is a novel antiproliferative agent with promising antiangiogenic effects. In the present study, the molecular mechanism underlying cytotoxic/antiangiogenic effects of BP-1T on tumour/non-tumour angiogenesis was evaluated. Evidences show that BP-1T exhibits potent cytotoxicity with prolonged activity and effectively regressed neovessel formation both in reliable non-tumour and tumour angiogenic models. The expression of CoCl2-induced HIF-1α was inhibited by BP-1T in various p53 (WT)-expressing cancer cells, including A549, MCF-7 and DLA, but not in mutant p53-expressing SCC-9 cells. Mechanistically, BP-1T mediates the HIF-1α proteasomal degradation by activating p53/MDM2 pathway and thereby downregulated HIF-1α-dependent angiogenic genes such as VEGF-A, Flt-1, MMP-2 and MMP-9 under hypoxic condition of in vitro and in vivo solid tumour, eventually leading to abolition of migration and invasion. Based on these observations, we conclude that BP-1T acts on HIF-1α degradation through p53/MDM2 proteasome pathway.

Synthesis and evaluation of novel benzophenone-thiazole derivatives as potent VEGF-A inhibitors

A series of 2-(4-benzoyl-phenoxy)-N-(4-phenyl-thiazol-2-yl)-acetamides (10a-n) were synthesized by multistep reaction sequence and all the compounds were well characterized for structural elucidation. The in vitro cytotoxicity of compounds 10a-n was evaluated against EAC and DLA cell lines using trypan blue dye exclusion method. Further MTT assay and LDH release assay, followed by in vivo studies on murine model were also evaluated. The compound 10h with a methyl and fluoro groups at benzophenone moiety and methoxy group at phenyl ring was in a leading position to exhibit the promising antiproliferative effect through translational VEGF-A inhibition.

A tumoural angiogenic gateway blocker, Benzophenone-1B represses the HIF-1α nuclear translocation and its target gene activation against neoplastic progression

Graphical abstract Figure. No Caption available. ABSTRACT Hypoxia is an important module in all solid tumours to promote angiogenesis, invasion and metastasis. Stabilization and subsequent nuclear localization of HIF‐1&agr; subunits result in the activation of tumour promoting target genes such as VEGF, MMPs, Flt‐1, Ang‐1 etc. which plays a pivotal role in adaptation of tumour cells to hypoxia. Increased HIF‐&agr; and its nuclear translocation have been correlated with pronounced angiogenesis, aggressive tumour growth and poor patient prognosis leading to current interest in HIF‐1&agr; as an anticancer drug target. Benzophenone‐1B ([4‐(1H‐benzimidazol‐2‐ylmethoxy)‐3,5‐dimethylphenyl]‐(4‐methoxyphenyl) methanone, or BP‐1B) is a new antineoplastic agent with potential angiopreventive effects. Current investigation reports the cellular biochemical modulation underlying BP‐1B cytotoxic/antiangiogenic effects. Experimental evidences postulate that BP‐1B exhibits the tumour specific cytotoxic actions against various cancer types with prolonged action. Moreover BP‐1B efficiently counteracts endothelial cell capillary formation in in‐vitro, in‐vivo non‐tumour and tumour angiogenic systems. Molecular signaling studies reveal that BP‐1B arrests nuclear translocation of HIF‐1&agr; devoid of p42/44 pathway under CoCl2 induced hypoxic conditions in various cancer cells thereby leading to abrogated HIF‐1&agr; dependent activation of VEGF‐A, Flt‐1, MMP‐2, MMP ‐9 and Ang‐1 angiogenic factors resulting in retarded cell migration and invasions. The in‐vitro results were reproducible in the reliable in‐vivo solid tumour model. Taken together, we conclude that BP‐1B impairs angiogenesis by blocking nuclear localization of HIF‐1&agr; which can be translated into a potent HIF‐1&agr; inhibitor.

The latex sap of the ‘Old World Plant’ Lagenaria siceraria with potent lectin activity mitigates neoplastic malignancy targeting neovasculature and cell death

Lifestyle and dietary modifications have contributed much to somatic genetic alteration which has concomitantly led to increase in malignant diseases. Henceforth, plant based and dietary interventions to mitigate and impede oncogenic transformation are in great demand. We investigated the latex sap (LSL) of the dietary Lagenaria siceraria vegetable, the first domesticated plant species with the potent lectin activity for its functional role against the tumor progression and its mechanism. LSL has markedly stimulated proliferation of lymphocytes and displayed strong cytotoxic activity against cancer both in-vitro and in-vivo. The tumor regression was paralleled with drastic reduction in tumoral neovasculature as evidenced from angiogenic parameters and abrogated related gene expressions. LSL has also triggered apoptotic signaling cascade in cancer cells through activation of caspase-3 mediated activation of endonuclease and inducing apoptotic cellular events. Collectively our study provides tangible evidences that latex sap from L. siceraria with immunopotentiating ability significantly regresses the tumor progression by targeting angiogenesis and inducing cell death.

Synthesis and antiproliferative activity of benzophenone tagged pyridine analogues towards activation of caspase activated DNase mediated nuclear fragmentation in Dalton’s lymphoma

A series of benzophenones possessing pyridine nucleus 8a-l were synthesized by multistep reaction sequence and evaluated for antiproliferative activity against DLA cells by in vitro and in vivo studies. The results suggested that, compounds 8b with fluoro group and 8e with chloro substituent at the benzoyl ring of benzophenone scaffold as well as pyridine ring with hydroxy group exhibited significant activity. Further investigation in mouse model suggests that compounds 8b and 8e have the potency to activate caspase activated DNase (endonuclease) which is responsible for DNA fragmentation, a primary hallmark of apoptosis and thereby inhibits the Daltons lymphoma ascites tumour growth.

Scutellarein antagonizes the tumorigenesis by modulating cytokine VEGF mediated neoangiogenesis and DFF-40 actuated nucleosomal degradation.

Neoplastic cells often reside in distinctive tumor hypoxia armed with a series of adaptive responses including oxidative stress, defective apoptotic machinery and neoangiogenesis, through that further confer cell survival improvement. Plants still acts as reservoir of natural chemicals to provide newer active pharmacophores. Scutellarein is flavones which has wide range of pharmacophoral effects. In our current research, scutellarein employed for targeting oxidative stress mediated tumor angiogenesis and apoptotic nuclear fragmentation. Experimental results revealed that scutellarein has antiproliferative index against multiple cancer cell lines and diminished the oxidative stress and tumor development of murine ascitic lymphoma & inflammatory hepatocellular carcinoma. Eventual consequences lead to reduced neovessel formation by abrogating angiogeneic factors cytokine-VEGF-A, Flt-1, HIF-1α, MMP-2 and MMP-9 and reversing of evading apoptosis by activating caspase-3 activated DNA fragmentation factor (DFF-40) mediated nucleosomal degradation. In summary, our experimental evidences suggest that scutellarein has strong potentiality to attenuate the tumor development by modulating sprouting neovasculature and DFF-40 mediated apoptosis.

Immunomodulatory glc/man-directed Dolichos lablab lectin (DLL) evokes anti-tumour response in vivo by counteracting angiogenic gene expressions: Immunomodulatory glc/man-directed DLL

Neovascularization and jeopardized immunity has been critically emphasized for the establishment of malignant progression. Lectins are the diverse class of carbohydrate interacting proteins, having great potential as immunopotentiating and anti‐cancer agents. The present investigation sought to demonstrate the anti‐proliferative activity of Dolichos lablab lectin (DLL) encompassing immunomodulatory attributes. DLL specific to glucose and mannose carbohydrate moieties has been purified to homogeneity from the common dietary legume D. lablab. Results elucidated that DLL agglutinated blood cells non‐specifically and displayed striking mitogenicity to human and murine lymphocytes in vitro with interleukin (IL)‐2 production. The DLL‐conditioned medium exerted cytotoxicity towards malignant cells and neoangiogenesis in vitro. Similarly, in‐vivo anti‐tumour investigation of DLL elucidated the regressed proliferation of ascitic and solid tumour cells, which was paralleled with blockade of tumour neovasculature. DLL‐treated mice showed an up‐regulated immunoregulatory cytokine IL‐2 in contrast to severely declined levels in control mice. Mechanistic validation revealed that DLL has abrogated the microvessel formation by weakening the proangiogenic signals, specifically nuclear factor kappa B (NF‐κB), hypoxia inducible factor 1α (HIF‐1 α), matrix metalloproteinase (MMP)‐2 and 9 and vascular endothelial growth factor (VEGF) in malignant cells leading to tumour regression. In summary, it is evident that the dietary lectin DLL potentially dampens the malignant establishment by mitigating neoangiogenesis and immune shutdown. For the first time, to our knowledge, this study illustrates the critical role of DLL as an immunostimulatory and anti‐angiogenic molecule in cancer therapeutics.

The anti-invasive role of novel synthesized pyridazine hydrazide appended phenoxy acetic acid against neoplastic development targeting matrix metallo proteases

Neoplastic metastasis is a major process where tumor cells migrate from the primary tumor and colonize at other parts of our body to form secondary tumor. Cancer incidences are rising and novel anti-neoplastic compounds with new mechanism of actions are essential for preventing cancer related deaths. In the current examination, a novel series of pyridazine analogues 6a-l was synthesized and evaluated against metastatic neoplastic cells. Experimental data postulated compound 6j has potential cytotoxic efficacy with prolonged activity against various cancer cells, including A549, HepG2, A498, CaSki and SiHa cells. Moreover, compound 6j arrests the A549 migration and invasions markedly by counteracting matrix metalloproteinase (MMP)-2 and MMP-9 expressions. Also, compound 6j proved its potentiality against Daltons solid lymphoma progression in-vivo by abridging MVD and MMP expressions. Compound 6j interacts with MMP-2 and MMP-9 by H- bond in-silico, thereby down regulates the MMPs action in tumourigenesis. Altogether, we concluded that compound 6j down regulates MMP-2 and MMP-9 and thereby impairs metastatic cancer cell migration and invasions which can be translated into a potent anti-neoplastic agent.